Apple is testing solar charging for iPhones. However, the problem with solar for an iPhone is that the phone is mostly in a pocket, so it doesn't get sunlight. When it's out during the day, it's usually indoors where there is not enough light to provide much juice.

Apple is considering solar power for the iWatch. Apple is reportedly developing a wearable computer for the wrist that will track health/fitness. Because an iWatch would be exposed to the sun, it might have solar charging.

Apple is trying out "magnetic induction" for the iWatch. This is charging without plugging in the iWatch. It would require a base charging station, then you rest the iWatch on that station to charge it. It seems unlikely Apple goes this route since SVP Phil Schiller said in 2012, "Having to create another device you have to plug into the wall is actually, for most situations, more complicated."

Apple is also testing charging the iWatch through motion. Really fancy watches don't have batteries. They power themselves by the motion on the wrist. An iWatch would presumably need more power than a Rolex, though, so we're not sure how much juice Apple can get from this method.

Anything that Apple develops for the iWatch, will likely get used in the iPhone. But, most of these ideas are "pie-in-the-sky" and seem unlikely to result in immediate improvements to battery life in new products.

The best way for any tech company to fix battery life is through improved computing. By making gadgets more efficient, battery life can improve. Batteries themselves seem to be stuck in the same place.

Nest CEO Tony Fadell tells the New York Times, "Hoping and betting on new battery technology to me is a fool’s errand ... Don’t wait for the battery technology to get there, because it’s incredibly slow to move."